HTTPS scanning and Synology NAS

Hi,

I'm using UTM 9(.409-9) Home Edition. I've installed the CA certificate on my Windows computers and Android Phones on my LAN behind the UTM to be able to scan HTTPS-traffic to these devices.  This works as expected ("avscantime="4164" on a HTTPS stream).

So, besides HTTPS scanning my phones and Windows machines, I'd also like to HTTPS scan the traffic to my Synology NAS (DSM 6.0.2-8451 Update 7). That means, I have to install the UTM's .p12 or .cer certificate on my NAS and that's where the trouble starts (illegal certificate message when importing the certificate on my NAS).

Has anybody out here been able to get HTTPS scanning working for a Synology NAS? And if so, how ..... ;-)

Thanks!!